When connecting a pipeline, or other conduit, to another pipeline or structure, a connection tool can be used to bring together the end of the pipelines to be connected. FIG. 1 shows a typical riser tower subsea installation featuring a number of situations where connections need to be made between conduits. For example a riser tower 10 is moored to the seabed 12 and connected to a surface production platform 14 such as a FPSO. Typical connections points that can be present in such an assembly exist between jumpers 16 that run from the riser tower 10 to flow line termination assemblies 18 (FTA), between FTAs 18 and pipelines 20 on the seabed 12 and between pipelines connecting production manifolds 22 and subsea trees 24 at the start of subsea oil well.
The conduits may be pipelines or cables for containing fluids, e.g. liquid or gas, and/or may contain electrical, hydraulic and/or optical services to be connected. Connections may be joining one length of a conduit to another, i.e. a midline connection, or connections may be at the start or finish point of the conduit, i.e. a termination connection, to another apparatus.
FIG. 2 shows the connection of a first conduit 26 with a second conduit 28 having a seal 30 between the end faces of the conduits and a closure mechanism 32, such as a clamp, around the hub of the connection. The point in the connection where the content of the conduits passes from one side of the connection to the other is defined as the interface 34.
In order for a satisfactory connection to be achieved the conduits must be sufficiently aligned for the liquid, gas, electricity, light etc to pass across the interface. The accuracy that needs to be achieved with the alignment can depend on the nature of the conduit and the nature of the contents of the conduits (liquid, gas, electricity, light etc). Typically the accuracy required will be specified in millimeters. Alignment is generally achieved through a series of steps carried out by a connection tool each step providing more accurate alignment until the final stage brings the conduits together with the accuracy required for the content of the conduit to pass across the interface and still remain contained within the conduit.
The conduits must also be bought into contact with each other with sufficient force and intimacy to ensure whatever seals or devices required to contain the contents of the conduits are retained and/or activated.
The conduits must then be able to be securely retained in the closed position by a closure device that resists both internal and external forces that the connection may be subjected to throughout its service life.
Currently available alignment and closure mechanisms can be both heavy and large. As the connector size and weight increases so does the cost of the equipment and processes required to install and operate the connector. This is particularly true when stiff conduits are being connected and or large diameter conduits are being connected where the loads required to achieve satisfactory alignment are high.
EP1956184 and US20010010782 describe methods and apparatus for aligning and connecting conduits.
It is an object of the invention to minimise the size and weight of the connecting tool required. This would also minimise the cost of equipment and the processes required to install the connection.